Engine knocking

[Letmeaddem]

So I recently got my mighty max running again only to find out that my engine is rattling. I drove it around the block and as I accelerated I heard the engine rattle like if some pins were lose and evert time I get the rpms past 3k it rattles louder and louder. What could it be ?

[geezer101]

Does it do it under load/throttle? Any check engine light? Could be running lean/detonating from a fuel pressure issue or tuning (O2 sensor out?). If you have bad bottom end bearings you will usually have low oil pressure accompanying the knock. With the engine running, pull a spark plug lead and listen for the knock. If it persists, kill the engine and test the next cylinder by removing the plug lead and repeating the process. If the knock stops, you have found the potential problem (could be more than 1 cylinder...)

[jamesw]

when was the last time you changed the oil? i know with my little truck when the oil starts to break down i will get a bit of a rattle . it,s like it,s saying ok now is the time to get me new oil lol another thing i do is put in some Lucas oil treatment works great on those tired old engines

[Letmeaddem]

Does it do it under load/throttle? Any check engine light? Could be running lean/detonating from a fuel pressure issue or tuning (O2 sensor out?). If you have bad bottom end bearings you will usually have low oil pressure accompanying the knock. With the engine running, pull a spark plug lead and listen for the knock. If it persists, kill the engine and test the next cylinder by removing the plug lead and repeating the process. If the knock stops, you have found the potential problem (could be more than 1 cylinder...)

No it starts up fin no check engine light either it's only when I get it up on speed. Oh okay great info I'm gonna try that when I get home. Do you think it could be the fuel pump causing the engine to misfire ?

[Letmeaddem]

when was the last time you changed the oil? i know with my little truck when the oil starts to break down i will get a bit of a rattle . it,s like it,s saying ok now is the time to get me new oil lol another thing i do is put in some Lucas oil treatment works great on those tired old engines

I just changed it last night. The oil it did have in it was super black but not gunky. I'll get some of that oil treatment hopefully it'll quiet it down

[geezer101]

Fuel pump being tired could be a reason why it's leaning out under load (bad fuel pressure regulator on FI trucks will have a similar symptom). Blocked fuel filter? Also if you're about to change the oil I'd recommend flushing the engine. Good chance it's never been done. It'll keep your engine oil fresh for longer as it won't be getting contaminated with all the sediment sitting in the oil galleries/sump, and it will also clear out the hydraulics. I did a write up on the procedure and members have given plenty of good feedback on the results -

http://www.mightyram50.net/vbulletin/showthread.php/2954-Why-didn-t-I-Think-Of-That?p=49688&viewfull=1#post49688

[tortron]

could be pinging? hard to tell without hearing it

[royster]

could be pinging? hard to tell without hearing it

When I first got my truck, I was able to run regular in it. Over time, I had to switch to mid-grade due to acceleration pinging. I don't think this was the fault of the truck, I think it has to do with gas manufacturing (and ethanol). It might be a good test to put some mid-grade in it, if you're running regular.

[geezer101]

When I first got my truck, I was able to run regular in it. Over time, I had to switch to mid-grade due to acceleration pinging. I don't think this was the fault of the truck, I think it has to do with gas manufacturing (and ethanol). It might be a good test to put some mid-grade in it, if you're running regular.

I am sure that some component of the fuel manufacturing process has changed. I hear new cars rattle under acceleration from the lights - something ain't right...

[royster]

Yup. Mid-grade is 30 - 40 cents a gallon more than regular, whereas it used to be only ten cents more. No question about the manufacturing process changing. Don't get Pennyman started about fuels !

[pennyman1]

too late - I'm on it. Try running Sta-Bil marine ethanol fuel treatment - it is an additive that negates the effects of ethanol in the gas. My Prelude sounded like a machine gun when revved up - once I added the treatment it quieted down to a whisper, and my gas mileage jumped 4-5 MPG. Use 1 oz to 10 gallons.

[Letmeaddem]

too late - I'm on it. Try running Sta-Bil marine ethanol fuel treatment - it is an additive that negates the effects of ethanol in the gas. My Prelude sounded like a machine gun when revved up - once I added the treatment it quieted down to a whisper, and my gas mileage jumped 4-5 MPG. Use 1 oz to 10 gallons.

Okay I'll give that a try

[jamesw]

Okay I'll give that a try
i think i will too

[Letmeaddem]

I couldn't find that sta-bil blue but would seafoam work ?

[geezer101]

Seafoam won't alter the octane rating of the fuel (raise it). It's meant to stop smoking engines and clean out combustion chambers. I still don't know if that stuff is really any good... you've got to be careful what you add to fuels and how much of it. Even ethanol in pump fuels causes grief.

[pennyman1]

Sta-Bil marine ethanol treatment is at most part stores, and boating supply shops as well

[Letmeaddem]

Seafoam won't alter the octane rating of the fuel (raise it). It's meant to stop smoking engines and clean out combustion chambers. I still don't know if that stuff is really any good... you've got to be careful what you add to fuels and how much of it. Even ethanol in pump fuels causes grief.

Oh okay just asking good info I wasn't too sure either.

[Letmeaddem]

I'm gonna go try my luck at my local Walmart cause the autozone where I live sucks they never have anything